U.S. patent application number 13/238613 was filed with the patent office on 2012-03-29 for printed circuit board design assisting device, method, and program.
This patent application is currently assigned to FUJITSU LIMITED. Invention is credited to Yoshiaki Hiratsuka, Kenji Nagase, Keisuke Nakamura, Tomoyuki Nakao, Yoshihiro Sawada.
Application Number | 20120079443 13/238613 |
Document ID | / |
Family ID | 45872000 |
Filed Date | 2012-03-29 |
United States Patent
Application |
20120079443 |
Kind Code |
A1 |
Nagase; Kenji ; et
al. |
March 29, 2012 |
PRINTED CIRCUIT BOARD DESIGN ASSISTING DEVICE, METHOD, AND
PROGRAM
Abstract
A printed circuit board design assisting device includes a frame
ground extraction section that extracts a ground pattern that is
provided in a surface layer of a printed circuit board and that is
to be connected to a metal component from design data on the
printed circuit board stored in a design data storage section to
store information for specifying the ground pattern in a data
storage section, an electrostatic discharge determination section
that performs a determination as to electrostatic discharge for the
ground pattern specified from the information stored in the data
storage section to store a determination result in a determination
result storage section, and an output section that outputs the
determination result stored in the determination result storage
section.
Inventors: |
Nagase; Kenji; (Kawasaki,
JP) ; Sawada; Yoshihiro; (Kawasaki, JP) ;
Hiratsuka; Yoshiaki; (Kawasaki, JP) ; Nakao;
Tomoyuki; (Kawasaki, JP) ; Nakamura; Keisuke;
(Kawasaki, JP) |
Assignee: |
FUJITSU LIMITED
Kawasaki
JP
|
Family ID: |
45872000 |
Appl. No.: |
13/238613 |
Filed: |
September 21, 2011 |
Current U.S.
Class: |
716/112 |
Current CPC
Class: |
G06F 30/398 20200101;
G06F 2119/10 20200101 |
Class at
Publication: |
716/112 |
International
Class: |
G06F 17/50 20060101
G06F017/50 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2010 |
JP |
2010-218146 |
Claims
1. A printed circuit board design assisting device comprising: a
frame ground extraction section that extracts a ground pattern,
which is provided in a surface layer of a printed circuit board and
that is to be connected to a metal component, from design data on
the printed circuit board stored in a design data storage section
to store information for specifying the ground pattern in a data
storage section; an electrostatic discharge determination section
that performs a determination as to electrostatic discharge for the
ground pattern specified from the information stored in the data
storage section to store a determination result in a determination
result storage section; and an output section that outputs the
determination result stored in the determination result storage
section.
2. The printed circuit board design assisting device according to
claim 1, wherein the electrostatic discharge determination section
determines that the ground pattern has an abnormality when the
ground pattern has an internal angle that measures less than a
predetermined amount.
3. The printed circuit board design assisting device according to
claim 1, wherein the electrostatic discharge determination section
determines that the ground pattern or a signal pattern has an
abnormality when the signal pattern is provided in the same layer
as the ground pattern and is located within a predetermined
distance from the ground pattern.
4. The printed circuit board design assisting device according to
claim 1, wherein the electrostatic discharge determination section
determines that the ground pattern has an abnormality when any
portion in which screw holes arranged along edges of the ground
pattern and directly or indirectly connected to the ground pattern
are spaced at intervals of a predetermined length or more.
5. The printed circuit board design assisting device according to
claim 1, wherein the electrostatic discharge determination section
determines that the ground pattern has an abnormality when an angle
between two adjacent sides defining edges of the ground pattern is
an angle within a predetermined range and there is no screw hole
directly or indirectly connected to a region inside the ground
pattern prescribed on the basis of an intersection point of the two
adjacent sides.
6. The printed circuit board design assisting device according to
claim 5, wherein the electrostatic discharge determination section
determines that the ground pattern has an abnormality when at least
one of the two adjacent sides has a second predetermined length or
more.
7. The printed circuit board design assisting device according to
claim 1, wherein the frame ground extraction section extracts the
ground pattern provided in the surface layer of the circuit board
when a region having a same center as a center of a screw hole and
obtained by multiplying a radius of the hole by a predetermined
number is provided inside the ground pattern or a hole for
connection of a lead pin of a spring connector is at least
partially provided inside the ground pattern.
8. The printed circuit board design assisting device according to
claim 1, wherein the electrostatic discharge determination section
stores information for specifying a location determined to have an
abnormality in the determination result storage section, and the
output section outputs the information for specifying the location
determined to have an abnormality stored in the determination
result storage section.
9. The printed circuit board design assisting device according to
claim 8, wherein the electrostatic discharge determination section
further stores information for identifying a category of the
abnormality in the determination result storage section, and the
output section further reads, from a correction method storage
section that stores data on a correction method associated with the
information for identifying the category of the abnormality, data
on the correction method in accordance with the information for
identifying the category of the abnormality stored in the
determination result storage section to output the read data on the
correction method.
10. A printed circuit board design assisting method executable by a
computer, the method comprising: extracting a ground pattern, which
is provided in a surface layer of a printed circuit board and that
is to be connected to a metal component, from design data on the
printed circuit board stored in a design data storage section;
storing information for specifying the ground pattern in a data
storage section; performing a determination as to electrostatic
discharge for the ground pattern specified from the information
stored in the data storage section; storing a determination result
in a determination result storage section; and outputting the
determination result stored in the determination result storage
section.
11. A non-transitory computer-readable medium storing a printed
circuit board design assisting program, which when executed by a
computer, causes the computer to execute: extracting a ground
pattern, which is provided in a surface layer of a printed circuit
board and that is to be connected to a metal component, from design
data on the printed circuit board stored in a design data storage
section; storing information for specifying the ground pattern in a
data storage section; performing a determination as to
electrostatic discharge for the ground pattern specified from the
information stored in the data storage section; storing a
determination result in a determination result storage section; and
outputting the determination result stored in the determination
result storage section.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority of the prior Japanese Patent Application No. 2010-218146,
filed on Sep. 29, 2010, the entire contents of which are
incorporated herein by reference.
FIELD
[0002] The embodiments discussed herein are related to a device and
a method that assist in designing a printed circuit board.
BACKGROUND
[0003] Electric devices and electronic devices are required to
provide electromagnetic non-interference and tolerance
(Electromagnetic Compatibility (EMC)). For example, when an
electrostatic voltage is applied to a metal portion, such as a
connector, exposed to a surface of an electronic device, noise due
to the voltage propagates through the metal portion of the device
and enters a printed circuit board to cause an erroneous operation.
CISPR 24, which is an international standard for information
devices, requires that the devices should operate normally when a
voltage of 4 kV is applied through contact discharge and a voltage
of 8 kV is applied through aerial discharge in an Electrostatic
Discharge (ESD) test.
[0004] For the electromagnetic tolerance, for example, there is
provided a technology for checking ESD tolerance by specifying a
location of application of static electricity and comparing the
distance from the specified location to a printed circuit board and
the distance from the specified location to a metal structure
provided to conduct the static electricity to the earth.
[0005] For the electromagnetic non-interference, there are provided
technologies for checking Electromagnetic Interference (EMI). For
example, in one technology, information on wiring of a printed
circuit board is referenced to check whether a guard ground, which
is a guard pattern of a ground attribute, is provided within a
prescribed distance from a signal pattern. In another technology,
it is checked whether a ground plane for preventing noise for a
signal pattern and a bypass capacitor for preventing noise for a
power supply are not connected to each other.
[0006] In recent years, for the electronic devices such as cellular
phones and personal computers, in particular, the component
mounting density has become higher, the material of housing
components has been changed from a metal to a resin, and the
structure of semiconductor devices has been changed along with size
and weight reductions, an increase in speed, and a reduction in
power consumption, and the ESD tolerance has been lowered
accordingly.
[0007] Previously, the ESD tolerance was successfully improved by
making modifications to the housing etc. in the device prototype
stage. However, housings with a reduced size and printed circuit
boards with a reduced mounting area do not allow such
modifications, and it is difficult to improve the ESD tolerance in
the same way as in the related art. Thus, it is preferable to take
ESD measures in the printed circuit board design stage. However,
there has not been provided any technology that allows specifying
from design data on the printed circuit board a location that may
be problematic from the viewpoint of ESD measures.
SUMMARY
[0008] According to an embodiment, a printed circuit board design
assisting device includes a frame ground extraction section that
extracts a ground pattern that is provided in a surface layer of a
printed circuit board and that is to be connected to a metal
component from design data on the printed circuit board stored in a
design data storage section to store information for specifying the
ground pattern in a data storage section, an electrostatic
discharge determination section that performs a determination as to
electrostatic discharge for the ground pattern specified from the
information stored in the data storage section to store a
determination result in a determination result storage section, an
output section that outputs the determination result stored in the
determination result storage section.
[0009] The object and advantages of the invention will be realized
and attained by at least the features, elements, and combinations
particularly pointed out in the claims.
[0010] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a functional block diagram of a printed circuit
board design assisting device;
[0012] FIGS. 2A to 2C illustrate a multi-layer circuit board
according to an embodiment;
[0013] FIG. 3 illustrates a pattern table stored in a design data
storage section;
[0014] FIG. 4 illustrates a hole table stored in the design data
storage section;
[0015] FIG. 5 illustrates a connector table stored in the design
data storage section;
[0016] FIG. 6 illustrates a printed circuit board design assisting
process;
[0017] FIG. 7 illustrates a frame ground determination process;
[0018] FIG. 8 illustrates a connector spring presence/absence
setting process;
[0019] FIG. 9 illustrates a list of spring connectors stored in a
spring connector storage section;
[0020] FIG. 10 illustrates a connector table stored in the design
data storage section with additional information on the presence or
absence of a spring;
[0021] FIG. 11 illustrates an error determination process;
[0022] FIGS. 12A and 12B illustrate an error determination for an
internal angle;
[0023] FIG. 13 illustrates a determination as to whether an
internal angle between two sides with various combinations of
lengths is to be checked;
[0024] FIG. 14 illustrates a screen for setting parameters for a
FRAME GROUND internal angle check;
[0025] FIG. 15 illustrates a FRAME GROUND-signal pattern gap
check;
[0026] FIG. 16 illustrates a screen for setting a parameter for the
FRAME GROUND-signal pattern gap check;
[0027] FIG. 17 illustrates an error determination process;
[0028] FIG. 18 illustrates a process for acquiring vertexes;
[0029] FIGS. 19A to 19D illustrate a predetermined range in which a
screw hole should be present;
[0030] FIG. 20 illustrates a check of corners and edges of a FRAME
GROUND;
[0031] FIG. 21 illustrates an error determination process;
[0032] FIG. 22 is a functional block diagram of a computer that
implements the embodiment;
[0033] FIG. 23 is a functional block diagram of a printed circuit
board design assisting device; and
[0034] FIG. 24 illustrates processes of a printed circuit board
design assisting method.
DESCRIPTION OF EMBODIMENTS
[0035] FIG. 1 is a functional block diagram of a printed circuit
board design assisting device according to an embodiment. The
printed circuit board design assisting device according to the
embodiment includes a design data storage section 101 that stores
design data generated by a CAD (Computer Aided Design) system, a
spring connector storage section 103 that stores a list of spring
connectors, a condition storage section 105 that stores parameters
for use in extraction of a frame ground and determination of an
error, a frame ground extraction section 107, a data storage
section 109, an error determination section 111, a determination
result storage section 113, a correction method storage section 115
that stores correction methods corresponding to the categories of
errors etc., and an output section 117.
[0036] The FRAME GROUND extraction section 107 extracts a FRAME
GROUND from the design data using data stored in the design data
storage section 101, the spring connector storage section 103, and
the condition storage section 105 to store data for specifying the
FRAME GROUND in the data storage section 109. The error
determination section 111 determines whether there is any problem
with the design data using data stored in the design data storage
section 101, the condition storage section 105, and the data
storage section 109 to store data for specifying a location
determined as an error and data indicating the category of the
error in the determination result storage section 113. The output
section 117 outputs the location determined as an error, a
correction method, etc., using data stored in the design data
storage section 101, the determination result storage section 113,
and the correction method storage section 115.
[0037] Next, the content of the processes performed by the printed
circuit board design assisting device illustrated in FIG. 1 will be
described with reference to FIGS. 2A to 2C and 21. The design data
storage section 101 stores design data on a printed circuit board
in advance. FIGS. 2A to 2C illustrate a schematic example of the
printed circuit board to be processed. FIGS. 2A to 2C illustrate a
multi-layer circuit board with a total of five layers. Third and
fourth layers are not illustrated. For such a printed circuit
board, data illustrated in FIGS. 3 to 5 are stored in the design
data storage section 101.
[0038] FIG. 3 illustrates an example of a pattern table stored in
the design data storage section 101. The pattern table has columns
for net name, configuration, layer information, type, and category.
In the net name field, the name for identification of a net
indicating a connection between terminals of components is
registered. As illustrated in FIG. 3, a plurality of patterns may
belong to the same net. In the configuration field, information for
specifying the shape of each pattern is registered. For example,
for a line pattern, the coordinates of the start and end points of
the line and the width of the line are registered. For an area
pattern, the coordinates of the vertexes defining the area are
registered in the order of connection. In the layer information
field, information for specifying which layer the pattern is
provided in is registered. For example, "L1" indicates the first
layer, and "L2" indicates the second layer. In the type field, the
type indicating the shape of the pattern is registered. Examples of
the type include "line" and "area". In the category field, the
category indicating the use of the pattern is registered. Examples
of the category include "signal", "power supply", and "ground
(GND)".
[0039] FIG. 4 illustrates an example of a hole table stored in the
design data storage section 101. The hole table has columns for
hole category, configuration, layer information, and type. In the
hole category field, the category indicating the shape of the hole
such as "circular" and "rectangular" is registered. In the
configuration field, information for specifying the shape of the
hole is registered. For example, for a circular hole, the center
coordinates and the radius are registered in the configuration
field. For a rectangular hole, the center coordinates and the
vertical and horizontal lengths are registered in the configuration
field. In the layer information field, information on the layer in
which the hole is provided is registered. In the type field, the
type of the hole such as "through" or "bottomed" is registered. In
case of a bottomed hole, the depth of the hole may be stored in the
configuration column.
[0040] FIG. 5 illustrates an example of a connector table stored in
the design data storage section 101. The connector table has
columns for model name, configuration, and layer information. In
the model name field, the name identifying the model of the
connector is registered. In the configuration field, the center
coordinates of the position at which the connector is disposed and
the vertical and horizontal lengths of the connector are
registered. In the layer information field, information for
specifying the layer in which the connector is disposed is
registered.
[0041] The process performed using such design data will be
described with reference to FIGS. 6 to 21. First, the FRAME GROUND
extraction section 107 performs a frame ground determination
process (FIG. 6: step S1). The FRAME GROUND determination process
will be described with reference to FIGS. 7 to 10.
[0042] The FRAME GROUND extraction section 107 performs a connector
spring presence/absence setting process (FIG. 7: step S11). The
connector spring presence/absence setting process will be described
with reference to FIGS. 8 and 9.
[0043] First, the FRAME GROUND extraction section 107 acquires one
unprocessed connector from the connector table in the design data
storage section 101 to store the acquired unprocessed connector in
the data storage section 109 (FIG. 8: step S31). Then, the FRAME
GROUND extraction section 107 searches the list of spring
connectors stored in the spring connector storage section 103 to
judge whether the model name of the connector to be processed is
registered (step S33).
[0044] The spring connector storage section 103 stores a list of
the model names of spring connectors such as that illustrated in
FIG. 9, for example. Spring connectors include a spring-like member
made of a metal. ESD noise can be dissipated to a housing by
causing the spring-like member to contact the housing, a shield
metal plate on a surface of a device at the same potential as the
housing, or the like when the connector is assembled to the device.
In the case where the model name of the connector to be processed
is included in the list of spring connectors, the FRAME GROUND
extraction section 107 registers the connector to be processed as
"with spring" in the data storage section 109 (step S35). For
example, as illustrated in FIG. 10, data indicating "without
spring" are initially registered for the connectors registered in
the connector table, and data indicating "with spring" are
registered for the connector to be processed. A column indicating
"with or without spring" may be added to the connector table
illustrated in FIG. 5.
[0045] In the case where it is judged in step S33 that the model
name of the connector to be processed is not registered in the list
of spring connectors, or after step S35, the FRAME GROUND
extraction section 107 judges whether there is any unprocessed
connector in the design data storage section 101 (step S37). In the
case where there is any unprocessed connector, the process returns
to step S31. In the case where there is no unprocessed connector,
the FRAME GROUND determination process is terminated to return to
the process in FIG. 7.
[0046] Returning to the description of the process in FIG. 7, the
FRAME GROUND extraction section 107 acquires one unprocessed ground
pattern in a surface layer from the pattern table in the design
data storage section 101 (FIG. 7: step S13). Specifically, the
FRAME GROUND extraction section 107 acquires one unprocessed
pattern, the layer information of which indicates a surface layer
(in the embodiment, the first layer or the fifth layer) and the
category of which is "GND". Then, the FRAME GROUND extraction
section 107 judges whether a screw hole registered in the hole
table in the design data storage section 101 meets a condition that
a region having the same center as the center of the screw hole and
having a radius obtained by multiplying the radius of the screw
hole by a predetermined number overlaps the ground pattern to be
processed (step S15).
[0047] For example, a screw hole that meets conditions that the
hole has a radius within a predetermined range and that the hole is
a circular hole penetrating through all the layers can be extracted
from the hole table. Then, it is judged whether a region centered
on the same coordinates as the center coordinates of the hole
registered in the hole table and having a radius obtained by
multiplying the radius of the hole by a predetermined number
overlaps the ground pattern specified from information from the
pattern table. Here, it is judged whether at least one of the holes
registered in the hole table meets the conditions. Specifically, it
is judged that a screw hole meets the above conditions either in
the case where the center of the screw hole is located inside the
ground pattern to be processed or in the case where the distance
between the center of the screw hole and a side of the ground
pattern to be processed that is the closest to the center of the
screw hole is equal to or less than a length obtained by
multiplying the radius of the screw hole by a predetermined
number.
[0048] A surrounding portion of the region having the same center
as the center of the screw hole and having a radius obtained by
multiplying the radius of the screw hole by a predetermined number
excluding the screw hole itself is contacted by the head portion of
a screw, a washer, or the like when the screw is fastened. In
general, the head portion of a screw contacts a region centered on
the screw hole obtained by multiplying the radius of the screw hole
by 1.4. For parameters such as the range of the radius as a
condition for a screw hole and a coefficient for use to multiply
the radius by a predetermined number, user set values may be stored
in advance in the condition storage section 105 to be read and used
by the FRAME GROUND extraction section 107. In the case where the
ground pattern and the screw are to be connected to each other, the
ground pattern is to be connected to the housing via the screw, a
spacer, or the like.
[0049] In the case where it is judged that there is any such screw
hole that the region having the same center as the center of the
screw hole and having a radius obtained by multiplying the radius
of the screw hole by a predetermined number overlaps the ground
pattern to be processed (step S17: Yes route), the process proceeds
to step S23. In the case where it is judged that there is no such
screw hole (step S17: No route), on the other hand, the FRAME
GROUND extraction section 107 judges whether there is any hole that
is to be connected to a lead pin of a spring connector and that
overlaps the ground pattern to be processed in the hole table in
the design data storage section 101 (step S19).
[0050] First, spring connectors can be specified in accordance with
whether or not data indicating "with spring" are registered for the
connectors registered in the connector table in the design data
storage section 109. Meanwhile, holes to which a lead pin of a
spring connector is to be connected can be specified as holes
provided in a region in which a spring connector is disposed on the
basis of regions in which the connectors are disposed registered in
the connector table and regions of the holes registered in the hole
table. Then, it is judged whether or not the holes to which a lead
pin of a spring connector is to be connected overlap the ground
pattern to be processed to judge whether there is any hole that
meets the conditions of step S19. Here, it is judged whether at
least one of the connectors with data indicating "with spring"
registered in the data storage section 109 meets the conditions. It
is also possible to first extract holes overlapping the ground
pattern to be processed and then judge whether the extracted holes
are to be connected to a spring connector. In the case where the
ground pattern and the spring connector are to be connected to each
other, the ground pattern is to be connected to the housing via the
spring connector.
[0051] In the case where it is judged in step S17 or step S21 that
there is any hole that meets the conditions, the FRAME GROUND
extraction section 107 registers the ground pattern to be processed
in a list of FRAME GROUNDs in the data storage section 109. For
example, information similar to the information in the pattern
table illustrated in FIG. 3 may be registered in the list of FRAME
GROUNDs. A flag indicating that the ground pattern is a FRAME
GROUND may be added to the pattern table.
[0052] In the case where it is judged in step S21 that there is no
hole that meets the conditions, or after step S23, the FRAME GROUND
extraction section 107 judges whether there is any unprocessed
ground pattern in a surface layer in the pattern table in the
design data storage section 101 (step S25). In the case where there
is any unprocessed ground pattern in a surface layer, the process
returns to step S13. In the case where there is no unprocessed
ground pattern in a surface layer, on the other hand, the FRAME
GROUND determination process is terminated to return to the process
in FIG. 6.
[0053] Returning to the description of the process in FIG. 6, the
error determination section 111 performs an error determination
process (step S3). The error determination process will be
described with reference to FIGS. 11 to 21.
[0054] First, the error determination section 111 acquires
parameters for use in the error determination process from the
condition storage section 105 (step S41). For example, parameters
for use in subsequent processes such as the internal angle of a
FRAME GROUND to be determined as an error, the length of sides to
be checked, the distance between a FRAME GROUND and a signal
pattern to be determined as an error, a parameter for specifying
the range in which a screw hole should be provided from a corner of
a FRAME GROUND, and the interval at which screw holes should be
disposed along an edge of a FRAME GROUND. Then, the error
determination section 111 acquires one unprocessed FRAME GROUND
from the list of FRAME GROUNDs stored in the data storage section
109 (step S43). Here, data on the FRAME GROUND with the data
structure illustrated in FIG. 3 are acquired.
[0055] Next, the error determination section 111 extracts an
unprocessed combination of two adjacent sides from the coordinates
of the vertexes defining the shape of the acquired FRAME GROUND
(step S45). Then, the error determination section 111 judges
whether the length of at least one of the two sides is equal to or
more than the length of sides to be checked acquired in step S41
and whether the internal angle between the two sides is equal to or
less than the internal angle of a FRAME GROUND to be determined as
an error acquired in step S41 (step S47).
[0056] Here, the internal angle of a FRAME GROUND to be determined
as an error is set to 85 degrees, for example. A strong electric
field tends to be produced at a pointed portion (in the embodiment,
a portion at an angle of 85 degrees or less) included in the shape
of a FRAME GROUND, and a dielectric breakdown may be caused at the
pointed portion. The internal angle of a FRAME GROUND to be
determined as an error is a parameter for use to judge whether
there is any such pointed portion. Meanwhile, the length of sides
to be checked is set to 0.1 mm, for example. On a printed circuit
board, successive short sides may form an arc-like shape. The
length of sides to be checked is a parameter for narrowing
locations for error determination by excluding angles between two
sides with a length less than a predetermined length.
[0057] Next, this determination will be described with reference to
FIGS. 12A, 12B, and 13. In FIG. 12A, angle c is 85 degrees or less.
In this case, if side a or side b has a length of 0.1 mm or more,
angle c is determined as an error. If sides a and b have a length
less than 0.1 mm, angle c is not determined as an error. FIG. 13
summarizes whether or not an internal angle between sides a and b
with various combinations of lengths is to be checked. In FIG. 12B,
on the other hand, angle f is more than 85 degrees. In this case,
it is decided whether or not angle f is to be checked in accordance
with the combination of the lengths of sides d and e as in FIG. 13.
Since angle f is more than 85 degrees, however, angle f is not
determined as an error irrespective of the lengths of sides d and
e.
[0058] An error determined in this step is typically attributable
to a designer, but may not be attributable to the designer. For
example, some printed circuit board design systems have a function
of automatically changing the shape of a ground pattern when the
designer draws a wiring pattern such that the wiring pattern and
the ground pattern are not connected to each other. Even in the
case where a portion of the ground pattern is changed into a
pointed shape by such a function, a problematic portion can be
specified by performing the determination as described above. In
addition, shapes that could only be observed by the designer
through enlarged display of the design data can be easily verified
by making a determination on the basis of the coordinates
registered in the pattern table.
[0059] The internal angle of a FRAME GROUND to be determined as an
error and the length of sides to be checked may be set in advance
by the user using an input screen such as that illustrated in FIG.
14, for example.
[0060] Then, in the case where it is determined that the
combination to be processed meets the conditions of step S47, the
error determination section 111 registers error data in the
determination result storage section 113 (step S49). Here, layer
information for specifying the layer in which the FRAME GROUND to
be processed is provided, the coordinates of three points for
specifying the two sides related to the combination to be
processed, and the error category are stored, for example. As the
error category, data for specifying the category of this error
determination are registered. For this error determination, data
such as "internal angle check" are registered, for example. The
registered data are subsequently used to present the location of
the error, a correction method, etc. Data with the data structure
illustrated in FIG. 3 may be registered to present the FRAME GROUND
itself, or the coordinates of the intersection point of the two
sides related to the combination to be processed may be registered
and a search may be performed around the registered coordinates in
the pattern table in the design data storage section 101 or the
like to present the location of the error.
[0061] In the case where it is determined that the combination to
be processed does not meet the conditions of step S47, or after
step S49, the error determination section 111 judges whether there
is any unprocessed combination of two adjacent sides (step S51). In
the case where there is any unprocessed combination, the process
returns to step S45.
[0062] In the case where it is judged that there is no unprocessed
combination, on the other hand, the error determination section 111
acquires one unprocessed signal pattern that is provided in the
same layer as the FRAME GROUND to be processed from the pattern
table in the design data storage section 101 (step S53). Here, a
pattern (including a via, a land, a pad, and so forth) that has the
same layer information as the FRAME GROUND to be processed and that
is in the "signal" category is acquired. Then, the error
determination section 111 judges whether the gap between the FRAME
GROUND and the signal pattern is equal to or less than the distance
between a FRAME GROUND and a signal pattern to be determined as an
error acquired in step S41 (step S55). Here, the distance between a
FRAME GROUND and a signal pattern to be determined as an error is
set to 2.0 mm, for example.
[0063] This step will be specifically described with reference to
FIG. 15. FIG. 15 illustrates a printed circuit board 1501, a FRAME
GROUND 1503, a pad 1505, an area pattern 1507, a via 1509, a line
pattern 1511, and a land 1513. The category for the area pattern
1507, the via 1509, the line pattern 1511, and the land 1513
registered in the pattern table is "signal". A search is performed
in such a printed circuit board 1501 for a gap with the smallest
size between a side of the FRAME GROUND 1503 and a side defining
the outer shape of each signal pattern, and it is judged whether
the smallest gap size is equal to or less than 2.0 mm.
[0064] If a signal pattern is provided near a FRAME GROUND on a
printed circuit board, ESD noise propagated through the FRAME
GROUND may affect the signal pattern. Thus, in the case where it is
judged in this step that the signal pattern is provided at a
distance of a predetermined value or less from the FRAME GROUND,
the FRAME GROUND or the signal pattern is determined as an error.
The distance between a FRAME GROUND and a signal pattern determined
as an error may be set in advance by the user using an input screen
such as that illustrated in FIG. 16, for example. For the pad 1505,
the via 1509, and the land 1513, the identification name, the
configuration (center coordinates, radius, vertical and horizontal
lengths, etc.), the layer information, the category (such as
"signal"), etc., may be registered in a table that is separate from
the pattern table.
[0065] Then, in the case where it is judged that the gap between
the FRAME GROUND and the signal pattern is a predetermined value or
less, the error determination section 111 registers error data in
the determination result storage section 113 (step S57). Here,
layer information for specifying the layer in which the FRAME
GROUND to be processed is provided, information indicating the
coordinates of the portion determined as an error, and the error
category are stored, for example. For the error category, data such
as "gap check" are registered, for example. For the information
indicating the coordinates of the portion determined as an error,
the coordinates of one or both of the FRAME GROUND to be processed
and the signal pattern may be registered, for example.
Alternatively, the start and end points of the line segment
indicating the smallest gap size may be registered. This error may
be considered as an error of the FRAME GROUND or an error of the
signal pattern, and can be resolved by correcting either the FRAME
GROUND or the signal pattern.
[0066] In the case where it is judged in step S55 that the gap
between the FRAME GROUND and the signal pattern is not equal to or
less than a predetermined value, or after step S57, the error
determination section 111 judges whether there is any unprocessed
signal pattern that has the same layer information as the FRAME
GROUND to be processed and that is in the "signal" category in the
pattern table in the design data storage section 101 (step S59). In
the case where it is judged that there is any unprocessed signal
pattern, the process returns to step S53. In the case where it is
judged that there is no unprocessed signal pattern, on the other
hand, the process proceeds to FIG. 17 via a terminal A.
[0067] Proceeding to the description of the process in FIG. 17, the
error determination section 111 acquires one unprocessed vertex
that meets predetermined conditions from the vertexes forming the
FRAME GROUND to be processed (step S61). Here, two adjacent sides
are first selected from the sides forming the FRAME GROUND. In the
case where the angle between the two sides is included in a range
of angle judged as a corner of a FRAME GROUND, the intersection
point of the two sides is acquired as the vertex to be processed.
An initial value or a user set value of the range of angle judged
as a corner of a FRAME GROUND is stored in advance in the condition
storage section 105, and acquired in step S41, for example. Here,
the range of angle judged as a corner of a FRAME GROUND is set to a
range excluding 175.0 degrees to 185.0 degrees. Coordinate data
indicating the acquired vertex are stored in the data storage
section 109.
[0068] In the case where the angle between two adjacent sides is
within a predetermined range, the two sides may be treated as a
single side. For example, in the case where the angle between the
two sides is equal to or more than 179.0 degrees and equal to or
less than 181.0 degrees, both end points of the two sides are
connected. In the case where two sides in such a relationship
appear successively, the sides as a whole may be treated as a
single side. It may be judged whether the angle between two
adjacent sides is within a predetermined range in the case where at
least one of the two sides has a predetermined length or more. For
example, it is judged whether the angle between two sides is in the
range excluding 175.0 degrees to 185.0 degrees discussed above in
the case where at least one of the two sides has a length of 35 mm
or more. Locations for error determination can be narrowed by
additionally imposing these conditions in the case where the
arc-like shape discussed above is to be processed. Initial values
or user set values of the example parameters may be stored in
advance in the condition storage section 105, and may be acquired
in step S41.
[0069] This step will be specifically described with reference to
FIG. 18. In FIG. 18, the angles between side hi and side ij,
between side ij and side jk, and between side jk and side kl are
each equal to or more than 179.0 degrees and equal to or less than
181.0 degrees. In this case, these sides are treated as side hl.
Side hl has a length of 35 mm or more. In this case, it is judged
whether or not each of the angles between side gh and side hi and
between side kl and side lm is within the range of angle judged as
a corner of a FRAME GROUND. The angle between side gh and side hi
is outside the range of 175.0 degrees to 185.0 degrees, and the
angle between side kl and side lm is within the range of 175.0
degrees to 185.0 degrees. In this case, vertex h is acquired in
this step, and vertex l is not acquired in this step.
[0070] Next, the error determination section 111 judges whether
there is any screw hole within a predetermined range from the
vertex to be processed (step S63). First, in step S41, a parameter
for specifying the range from a corner of a FRAME GROUND to a screw
hole that should be provided has been acquired from the condition
storage section 105. Here, the parameter is set to 10.0 mm. FIGS.
19A to 19D illustrate the predetermined range in this step. For
example, as illustrated in FIGS. 19A and 19B, a rhombus (or square)
range defined by two sides extending over 10.0 mm from the vertex
to be processed in directions along two sides forming the FRAME
GROUND and two sides extending over 10.0 mm in parallel with the
two 10.0 mm-long sides and provided inside the FRAME GROUND is used
as the predetermined range. Then, it is judged in this step whether
there is any screw hole in such a predetermined range.
[0071] Alternatively, as illustrated in FIG. 19C, for example, a
rhombus range defined by two sides forming the FRAME GROUND and two
sides provided opposite the two sides forming the FRAME GROUND and
at a distance of 10.0 mm from the two sides forming the FRAME
GROUND may be used as the predetermined range. In the case where
the angle between two sides forming the FRAME GROUND is more than
180 degrees, as illustrated in FIG. 19D, for example, a hook-shaped
range surrounded by two sides extending over 10.0 mm from the
vertex in directions along the two sides forming the FRAME GROUND,
lines passing through end points of the two sides to extend
perpendicularly to the two sides, and lines extending in parallel
with the two sides forming the FRAME GROUND and provided inside the
FRAME GROUND and at a distance of 10.0 mm from the two sides
forming the FRAME GROUND may be used as the predetermined range.
Further, a region provided inside the FRAME GROUND and within a
predetermined distance from the intersection point of two sides
forming the FRAME GROUND may be used as the predetermined
range.
[0072] Then, it is judged whether there is any screw hole that
meets a condition that a region having the same center as the
center of the screw hole and having a radius obtained by
multiplying the radius of the screw hole by a predetermined number
overlaps the predetermined range. The condition for a screw hole
and the judgment as to whether or not a region having the same
center as the center of the screw hole and having a radius obtained
by multiplying the radius of the screw hole by a predetermined
number overlaps a certain region are the same as in step S15. In
the case where there is any screw hole that meets the condition of
this step, coordinate data for specifying the screw hole are stored
in the data storage section 109 in correlation with the vertex to
be processed. In the case where there is a plurality of screw holes
that meet the condition of this step, coordinate data on one screw
hole, the center of which is the closest to the vertex to be
processed, may be stored, for example.
[0073] ESD noise tends to flow through the edges of the FRAME
GROUND. Thus, a strong electric field tends be produced at the
corners of the FRAME GROUND, even if the internal angle of the
corners is not judged as an error in step S47. ESD noise can be
easily dissipated to the housing via a screw by providing a screw
hole at the corners of the FRAME GROUND as discussed above.
Therefore, a corner of the FRAME GROUND, within the predetermined
range from which there is no screw hole, is specified in this step.
Even in the case where a screw hole is provided partially or wholly
outside the predetermined range, for example, the head portion of a
screw provided in the screw hole contacts the predetermined range
if a region having the same center as the center of the screw hole
and having a radius obtained by multiplying the radius of the screw
hole by a predetermined number overlaps the predetermined range.
Therefore, ESD noise can be dissipated via the screw.
[0074] This step will be specifically described with reference to
FIG. 20. In FIG. 20, outside surrounding lines indicate the outer
shape of the FRAME GROUND. Small black circles each indicate a
vertex to be acquired in step S61. Hatched ranges each indicate a
predetermined range in which a screw hole should be provided. Large
black circles each indicate a screw hole provided within the
predetermined range from the vertex to be acquired in step S61.
Because there is no screw hole in hatched range n at the upper left
of FIG. 20, it is judged that there is no screw hole that meets the
condition of this step in hatched range n. Screw hole p is provided
partially outside the predetermined range, and screw hole q is
provided wholly outside the predetermined range. Because a region
having the same center as the center of each of the screw holes and
having a radius obtained by multiplying the radius of each of the
screw holes by 1.4 overlaps the predetermined range, however, it is
judged that each of screw holes p and q meets the condition of this
step.
[0075] In the case where there is no screw hole within the
predetermined range from the vertex to be processed, the error
determination section 111 registers error data in the determination
result storage section 113 (step S65). Here, layer information for
specifying the layer in which the FRAME GROUND to be processed is
provided, the coordinates for specifying the vertex to be
processed, and the error category are stored, for example. For the
error category, data such as "FRAME GROUND corner check" are
registered, for example. Coordinate data indicating a range in
which a screw hole should be provided or the like may alternatively
be stored.
[0076] In the case where there is any screw hole within the
predetermined range from the vertex to be processed, or after step
S65, the error determination section 111 judges whether there is
any unprocessed vertex that meets the conditions of step S61 in the
FRAME GROUND to be processed (step S67). In the case where there is
any unprocessed vertex, the process returns to step S61.
[0077] In the case where there is no unprocessed vertex, on the
other hand, the error determination section 111 searches the
determination result storage section 113 to judge whether there is
any error related to the FRAME GROUND corner check (step S68).
Here, it is judged whether there are any data with "FRAME GROUND
corner check" registered in the error category field in the
determination result storage section 113, for example. In the case
where there is any error related to the FRAME GROUND corner check,
the process proceeds to the process in FIG. 21 via a terminal B,
and returns to the process in FIG. 6 after the error determination
process is terminated. Because subsequent error handling is
performed on the assumption that there are screw holes at the
corners of the FRAME GROUND, a preliminary correction is promoted
here.
[0078] In the case where there is no error related to the FRAME
GROUND corner check, the error determination section 111 acquires
one unprocessed screw hole from the screw holes registered in the
data storage section 109 in step S63 (step S69).
[0079] Next, the error determination section 111 performs a search
along the sides forming the FRAME GROUND to extract a screw hole
provided adjacent to the screw hole to be processed (step S71).
First, a belt-like range between sides extending in parallel with
the sides forming the FRAME GROUND and provided inside the FRAME
GROUND and at a distance of 10.0 mm from the sides forming the
FRAME GROUND and the sides forming the FRAME GROUND is set as the
predetermined range. An interval of 70.0 mm, for example, is set as
a predetermined interval. Initial values or user set values of the
predetermined range and the predetermined interval may be stored in
advance in the condition storage section 105, and may be acquired
in step S41. The value of the distance parameter used in this step,
which is 10.0 mm in the example, may be the same as or different
from the value of the parameter for specifying the range in which a
screw hole should be provided from a corner of a FRAME GROUND used
in step S63.
[0080] Then, a search is performed in either direction along the
sides forming the FRAME GROUND, for example, to extract a nearby
screw hole that meets the condition that a region having the same
center as the center of the screw hole and having a radius obtained
by multiplying the radius of the screw hole by a predetermined
number overlaps the predetermined range. It is also confirmed that
the interval between the extracted screw hole and the screw hole to
be processed is 70.0 mm or less.
[0081] As discussed above, ESD noise tends to flow through the
edges of the FRAME GROUND. Thus, ESD noise can be easily dissipated
to the housing via a screw by providing a screw hole along the
edges of the FRAME GROUND. Therefore, in this step, it is confirmed
that screw holes are provided at predetermined intervals along the
edges of the FRAME GROUND. Even in the case where a screw hole is
provided partially or wholly outside the predetermined range, such
a screw hole is treated as meeting the conditions of this step if a
region having the same center as the center of the screw hole and
having a radius obtained by multiplying the radius of the screw
hole by a predetermined number overlaps the predetermined range, as
in steps S15 and S63.
[0082] In FIG. 20, a belt-like range between outside surrounding
lines and inside surrounding lines indicates the predetermined
range in this step. Large black circles each indicate a screw hole
that meets the conditions of step S63, and gray circles each
indicate a screw hole extracted in step S71. Screw hole r is
provided partially outside the predetermined range, and screw hole
s is provided wholly outside the predetermined range. Because a
region having the same center as the center of each of the screw
holes and having a radius obtained by multiplying the radius of
each of the screw holes by 1.4 overlaps the predetermined range,
however, it is judged that each of screw holes r and s meets the
condition of this step. In this step, it is judged whether the
centers of such screw holes are provided continuously at intervals
of 70.0 mm or less. In FIG. 20, a circle with a radius of 35.0 mm
is illustrated around each of the screw holes for the purpose of
illustration. That is, it is judged in this step that the interval
between screw holes is more than 70.0 mm at a portion not covered
by the circles. Specifically, it is judged that the interval
between screw hole t and screw hole u is more than 70.0 mm.
[0083] Then, the error determination section 111 judges whether the
screw hole extracted in step S71 is provided within the
predetermined interval (step S73). In the case where the screw hole
is not provided within the predetermined interval, the error
determination section 111 registers error data in the determination
result storage section 113 (step S75). Here, layer information for
specifying the layer in which the FRAME GROUND to be processed is
provided, information for specifying the portion judged as an
error, and the error category are stored, for example. For the
error category, data such as "FRAME GROUND edge check" are
registered, for example. For the information for specifying the
portion judged as an error, the center coordinates of the two screw
holes judged to be located away from each other by more than the
predetermined interval are registered, for example. Coordinates for
specifying a range in which a screw hole should be provided or the
like may alternatively be registered.
[0084] In the case where the screw hole extracted in step S71 is
provided within the predetermined interval, on the other hand, or
after step S75, the error determination section 111 judges whether
the extracted screw hole is identical to the screw hole acquired in
step S69 (step S77). In steps S71 to S77, searches for a screw hole
are performed along the sides forming the FRAME GROUND around the
FRAME GROUND, and the process is repeated until the screw hole to
be processed initially set in step S69 is extracted. In the case
where the extracted screw hole is different from the screw hole
acquired in step S69, the screw hole extracted in step S71 is set
as a new screw hole to be processed, and the process returns to
step S71. In the case where the extracted screw hole is identical
to the screw hole acquired in step S69, on the other hand, the
process proceeds to FIG. 21 via a terminal C.
[0085] Proceeding to the process in FIG. 21, the error
determination section 111 judges whether there is any unprocessed
FRAME GROUND in the data storage section 109 (step S79). In the
case where there is any unprocessed FRAME GROUND, the process
returns to step S43 via a terminal D. In the case where there is no
unprocessed FRAME GROUND, on the other hand, the error
determination process is terminated to return to the process in
FIG. 6.
[0086] Returning to the description of the process in FIG. 6, the
output section 117 outputs error information using data stored in
the design data storage section 101, the determination result
storage section 113, and the correction method storage section 115
(step S5). Here, the output section 117 generates a list for
presenting to the user the error information stored in the
determination result storage section 113, for example, to output
the generated list. An error correction method associated with the
error category is stored in advance in the correction method
storage section 115. Examples of the error correction method are as
follows. For "internal angle check", a message indicating that a
correction should be made to eliminate any pointed portion at which
the internal angle of the FRAME GROUND is a predetermined angle or
less has been registered. Likewise, for "gap check", a message
indicating that a correction should be made to increase the
distance between the FRAME GROUND and the signal pattern to be more
than a predetermined distance. For "FRAME GROUND corner check", a
message indicating that a correction should be made to provide a
screw hole within a predetermined range from the corners of the
FRAME GROUND. For "FRAME GROUND edge check", a message indicating
that a correction should be made to provide screw holes at
predetermined intervals along the edges of the FRAME GROUND.
[0087] Here, the output section 117 acquires information for
displaying the circuit configuration around the location of the
error from the tables stored in the design data storage section 101
on the basis of the coordinate data and the layer information
indicating the location of the error registered in the
determination result storage section 113 to output an enlarged view
around the location of the error, for example. Also, the output
section 117 acquires a correction method from the correction method
storage section 115 on the basis of the error category registered
in the determination result storage section 113 to output the
acquired correction method. Specific numerical values of the angle
or the distance for the location judged as an error may be held in
the error determination process so that a message such as "Only Y
mm away; should be X mm away" can be output in this step. The
output section 117 may suggest a possible effect of the location
judged as an error. Rather than outputting a list of the error
information, the error information may be displayed sequentially so
that the user can correct the design data through a dialog. The
output may be made to the user, and further the user may be allowed
to correct the design data, at the timing when error data are
registered in the error determination process.
[0088] In the case where the user has corrected the design data,
the printed circuit board design assisting device performs the
process again in response to an instruction from the user or
automatically, for example. The error determination process is
preferably performed all through because a correction may resolve
one error and cause another error at the same time. In the case
where it is judged in step S68 that there is any error in the FRAME
GROUND corner check, the error determination process etc. is
performed after the design data are corrected. At this time, the
process may be resumed at step S61, for example.
[0089] In the embodiment, the FRAME GROUND edge check in steps S69
to S77 is performed in the case where there is no error in the
FRAME GROUND corner check in steps S61 to S67. However, the FRAME
GROUND edge check may be performed without terminating the process
in step S68. In this case, a screw hole is acquired in step S69
from the predetermined range in step S71, for example, so that the
FRAME GROUND edge check is performed independently of the FRAME
GROUND corner check.
[0090] In the FRAME GROUND edge check, a plurality of screw holes
that meet the conditions of step S63 may be first acquired, and it
may then be confirmed that screw holes are provided at
predetermined intervals between the acquired screw holes.
[0091] By performing the process described above, a location that
may be problematic in terms of ESD tolerance can be specified from
design data on a printed circuit board. That is, a ground pattern
to which the designer of the printed circuit board should pay
attention from the viewpoint of ESD measures can be extracted.
[0092] While an embodiment of the present technology has been
described above, the present technology is not limited thereto. For
example, the functional block diagram is merely exemplary, and does
not necessarily coincide with the actual program module
configuration. In addition, the steps in the process may be
performed in a different order or in parallel with each other
unless the results of the process are changed. Further, the tables
of the design data illustrated in FIGS. 3 to 5 are also exemplary,
and may include different data items.
[0093] The printed circuit board design assisting device discussed
above is implemented by a computer device including, as illustrated
in FIG. 22, a memory 2501, a CPU 2503, a hard disk drive (HDD)
2505, a display control section 2507 connected to a display device
2509, a drive device 2513 for a removable disk 2511, an input
device 2515, and a communication control section 2517 for
connection to a network. The components of the computer device are
connected to each other via a bus 2519. An Operating System (OS)
and an application program for performing the process according to
the embodiment are stored in the HDD 2505, and are read from the
HDD 2505 into the memory 2501 to be executed by the CPU 2503. The
CPU 2503 controls the display control section 2507, the
communication control section 2517, and the drive device 2513 in
accordance with the content of the process of the application
program to cause the display control section 2507, the
communication control section 2517, and the drive device 2513 to
perform a predetermined operation. Data that are being processed
are mainly stored in the memory 2501, but may be stored in the HDD
2505. In the embodiment of the present technology, the application
program for performing the process discussed above is distributed
in the removable disk 2511, which is computer-readable, to be
installed on the HDD 2505 from the drive device 2513. The
application program may also be installed on the HDD 2505 via a
network such as the Internet and the communication control section
2517. Such a computer device achieves the variety of functions
discussed above through organic cooperation of hardware such as the
CPU 2503 and the memory 2501 and programs such as the OS and the
application program.
[0094] The printed circuit board design assisting device according
to the embodiment includes: (A) a frame ground (FRAME GROUND)
extraction section (FIG. 23: 2303) that extracts a ground pattern
that is provided in a surface layer of a printed circuit board and
that is to be connected to a metal component from design data on
the printed circuit board stored in a design data storage section
(FIG. 23: 2301) to store information for specifying the ground
pattern in a data storage section (FIG. 23: 2305); (B) an
electrostatic discharge determination section (FIG. 23: 2307) that
performs a determination as to electrostatic discharge for the
ground pattern specified from the information stored in the data
storage section to store a determination result in a determination
result storage section (FIG. 23: 2309); and (C) an output section
(FIG. 23: 2311) that outputs the determination result stored in the
determination result storage section.
[0095] An electrostatic voltage may be applied to a metal component
exposed to the outside of a device, and ESD noise may flow through
a ground pattern connected to such a metal component. A ground
pattern connected to a metal component may serve as a path for
dissipating ESD noise to a housing via the metal component. In a
multi-layer circuit board, in particular, ESD noise propagates via
a surface layer, and therefore a ground pattern in the surface
layer is important in terms of ESD measures. Thus, a ground pattern
to which a designer should pay attention for ESD measures can be
presented by performing a determination as to electrostatic
discharge for the ground pattern discussed above.
[0096] The electrostatic discharge determination section discussed
above may determine that the ground pattern has an abnormality in
the case where the ground pattern has an internal angle that is a
predetermined angle or less. A strong electric field tends to be
produced at a pointed portion in the ground pattern, which may
cause a dielectric breakdown. Such a problematic portion can be
determined as an abnormality by performing the determination
discussed above.
[0097] The electrostatic discharge determination section discussed
above may determine that the ground pattern or a signal pattern has
an abnormality in the case where the signal pattern is provided in
the same layer as the ground pattern and within a predetermined
distance from the ground pattern. ESD noise flowing through the
ground pattern may be coupled to the signal pattern depending on
the distance between the ground pattern and the signal pattern.
Such a problematic portion can be determined as an abnormality by
performing the determination discussed above.
[0098] The electrostatic discharge determination section may
determine that the ground pattern has an abnormality in the case
where there is a portion in which screw holes arranged along edges
of the ground pattern and directly or indirectly connected to the
ground pattern are spaced at intervals of a predetermined length or
more. More specifically, the electrostatic discharge determination
section may determine that the ground pattern has an abnormality in
the case where there is any portion in which screw holes that are
arranged along edges of the ground pattern and that contact a
predetermined range inside the ground pattern and screw holes for
screws that contact the predetermined range when the screws are
fastened are spaced at intervals of a predetermined length or more.
ESD noise can be dissipated to a housing by connecting the ground
pattern to the housing via the screws. ESD noise tends to flow
through the edges of the ground pattern. Thus, ESD noise can be
easily dissipated to the housing by providing screw holes along the
edges of the ground pattern at intervals less than the
predetermined length. Thus, a location that may need a correction
can be specified by performing the determination discussed
above.
[0099] The electrostatic discharge determination section may
determine that the ground pattern has an abnormality in the case
where an angle between two adjacent sides defining edges of the
ground pattern is an angle within a second predetermined range and
there is no screw hole directly or indirectly connected to a region
inside the ground pattern prescribed on the basis of an
intersection point of the two adjacent sides. More specifically,
the electrostatic discharge determination section may determine
that the ground pattern has an abnormality in the case where an
angle between two adjacent sides defining edges of the ground
pattern is an angle within a second predetermined range and there
is no screw hole that contacts a region inside the ground pattern
prescribed on the basis of an intersection point of the two
adjacent sides or no screw hole for a screw that contacts the
region when the screw is fastened. ESD noise tends to flow through
the edges of the ground pattern. A strong electric field may be
produced at such an intersection point of the two sides as with the
pointed portion discussed above. ESD noise can be easily dissipated
to the housing if there is a screw hole connected to the region
prescribed on the basis of the intersection point. Thus, a location
that may need a correction can be specified by performing the
determination discussed above.
[0100] The electrostatic discharge determination section may
determine that the ground pattern has an abnormality in the case
where at least one of the two adjacent sides has a second
predetermined length or more. The number of intersection points of
two sides discussed above may be excessive in the case where an
arc-like shape is formed by short adjacent sides, for example.
Intersection points for determination can be narrowed by
additionally imposing a condition that at least one side has a
predetermined length or more.
[0101] The frame ground extraction section may extract the ground
pattern provided in the surface layer of the circuit board in the
case where a region having the same center as a center of a screw
hole and obtained by multiplying a radius of the hole by a
predetermined number is provided inside the ground pattern or a
hole for connection of a lead pin of a spring connector is at least
partially provided inside the ground pattern. If a region obtained
by multiplying the radius of a screw hole by a predetermined number
is provided inside the ground pattern, it is considered that the
ground pattern is to contact the head portion of a screw, a washer,
or the like to be connected to the housing via the screw, a spacer,
or the like. In the case where the ground pattern and the spring
connector are to be connected to each other, meanwhile, it is
considered that the ground pattern is to be connected to the
housing via the spring connector. That is, such a ground pattern
functions as a frame ground, and may serve as a path for
propagating ESD noise. Such a ground pattern can be extracted in
the manner discussed above.
[0102] The electrostatic discharge determination section may store
information for specifying a location determined to have an
abnormality in the determination result storage section, and the
output section may output the information for specifying the
location determined to have an abnormality stored in the
determination result storage section. This allows the user to
specify the location determined to have an abnormality.
[0103] The electrostatic discharge determination section may
further store information for identifying a category of the
abnormality in the determination result storage section, and the
output section may further read, from a correction method storage
section that stores data on a correction method associated with the
information for identifying the category of the abnormality, data
on the correction method in accordance with the information for
identifying the category of the abnormality stored in the
determination result storage section to output the read data on the
correction method. This allows presenting how the design data may
be corrected to the user.
[0104] The printed circuit board design assisting method according
to the embodiment includes: (A) extracting a ground pattern that is
provided in a surface layer of a printed circuit board and that is
to be connected to a metal component from design data on the
printed circuit board stored in a design data storage section to
store information for specifying the ground pattern in a data
storage section (FIG. 24: 2401); (B) performing a determination as
to electrostatic discharge for the ground pattern specified from
the information stored in the data storage section to store a
determination result in a determination result storage section
(FIG. 24: 2403); and (C) outputting the determination result stored
in the determination result storage section (FIG. 24: 2405).
[0105] A program for causing a computer to perform processes
according to the above method can be prepared. The program is
stored in a computer-readable storage medium or storage device such
as a flexible disk, a CD-ROM, a magneto-optical disk, a
semiconductor memory, or a hard disk, for example. Intermediate
process results are temporarily stored in a storage device such as
a main memory.
[0106] The embodiments can be implemented in computing hardware
(computing apparatus) and/or software, such as (in a non-limiting
example) any computer that can store, retrieve, process and/or
output data and/or communicate with other computers. The results
produced can be displayed on a display of the computing hardware. A
program/software implementing the embodiments may be recorded on
computer-readable media comprising computer-readable recording
media. The program/software implementing the embodiments may also
be transmitted over transmission communication media. Examples of
the computer-readable recording media include a magnetic recording
apparatus, an optical disk, a magneto-optical disk, and/or a
semiconductor memory (for example, RAM, ROM, etc.). Examples of the
magnetic recording apparatus include a hard disk device (HDD), a
flexible disk (FD), and a magnetic tape (MT). Examples of the
optical disk include a DVD (Digital Versatile Disc), a DVD-RAM, a
CD-ROM (Compact Disc-Read Only Memory), and a CD-R (Recordable)/RW.
An example of communication media includes a carrier-wave signal.
The media described above may be non-transitory media.
[0107] All examples and conditional language recited herein are
intended for pedagogical purposes to aid the reader in
understanding the principles of the invention and the concepts
contributed by the inventor to furthering the art, and are to be
construed as being without limitation to such specifically recited
examples and conditions. Although the embodiments of the present
inventions have been described in detail, it should be understood
that various changes, substitutions, and alterations could be made
hereto without departing from the spirit and scope of the
invention.
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